Improvement in nut and bolt locks



f of Orange, New Jersey,

, the upsetting of the screw-threads.

UNITED STATES PATENT EEIoE HA'YWARD A.. HARVEY, OF ORANGE, NEW JERSEY.

IMPROVEMENT INNUT AND BOLT LocKs.

Speoication forming part of Letters Patent No. 197,467, dated November 27, 1877 application l'ed June 4, 1877. l

To' all whom it may concern:

Be it known that I, HAYWARD A. HARVEY,

haveinvented an Improvement in Screw Bolts and Nuts, of which the following` is a specification:

My improvement relates to that class of screw-bolts in which the nut is intended to be held in the position in which it is applied by Heretofore this has been accomplished by janunin g the nut hard against the object through which the bolt passed, the bolt-thread having been constructed of suitable form to yield in the required direction.

In my present invention upsetting of the threads by uniform pitch. In this threads, respectively, is `so proportioned that a nut can be easily started on the end of the bolt, and will turn freely for about two and a half revolutions, .at which point the interference of the threads causes such friction thatthe nut cannot be further turned Without the application of power suiicient to upset the hreads upon each other. The extent of this upsetting of the threads depends upon the Anumber of turns which are thus forcibly given to the nut.

'- The bolt is constructed with reference to use I1n objects of ascertained thickness, and the dlil'erential threads are proportioned with reference to being made to acquire the desired degree of upsetting when the nut has brought up against the surface of the object through which the bolt is inserted. v

The effect of upsetting the thread in this way is not only to make the nut hold its position with a stron g gripe, but to render the nut incapable of being unscrewed from the bolt without the application of sufcient force to set its threads back somewhat to accommodate them to the finer pitch of the thread near the end of the bolt.

In the drawings,

bolt to the polnt where the nut-thread binds on the bolt-thread; and Fig. 2 represents the nut in its nal position, and shows the charac ter of the modification in the form of the nut-thread due to the forcible driving of the nut upon the coarser part of the bolt-thread.

In the drawings, A represents the-shank of the bolt; B, the head, and C the nut. The bolt-thread a is an ordinary V-thread, and has a pitch gradually diminishing from its point of commencement al to the en d a2 of the bolt.

and a nut, one or both of which has a screW- thread oi'- diif'erential or varying pitch, 'as and for the purpose set forth.

'H. A. HARVEY.

Witnesses ASA FARE, EDWD. PAYsoN. 

